Monday, July 30, 2012

No Autism Epidemic, Just Better Diagnostic Tools

Annals of Science

In an article in Discover, Emily Willingham writes rather persuasively using data and facts that autism is not on the rise in the industrialized world, but, rather, has been better diagnosed the last few years. To its credit, psychiatric medicine has developed more sophisticated tools to diagnose autism, including recently adopted categories—like Asperger's syndrome— that were non-existent in the past:
Asperger’s syndrome, a form of autism sometimes known as “little professor syndrome,” is in the same we-didn’t-see-it-before-and-now-we-do situation. In 1981, noted autism researcher Lorna Wing translated and revivified Hans Asperger’s 1944 paper describing this syndrome as separate from Kanner’s autistic disorder, although Wing herself argued that the two were part of a borderless continuum. Thus, prior to 1981, Asperger’s wasn’t a diagnosis, in spite of having been identified almost 40 years earlier. Again, the official prevalence was zero before its adoption by the medical community.
And so, here we are today, with two diagnoses that didn’t exist 70 years ago (plus a third, even newer one: PDD-NOS) even though the people with the conditions did. The CDC’s new data say that in the United States, 1 in 88 eight-year-olds fits the criteria for one of these three, up from 1 in 110 for its 2006 estimate. Is that change the result of an increase in some dastardly environmental “toxin,” as some argue? Or is it because of diagnostic changes and reassignments, as happened when autism left the schizophrenia umbrella?
Scientific studies show that the societal level of autism is around one percent, a figure that many studies show is stable and similar from country to country and between generations. What might seem like a rampant increase to non-scientists—and notably the purveyors of fear—is essentially the success of campaigns to increase awareness of a disorder in accordance to DSM-IV, the accepted diagnostic manual of psychiatry. "Because of greater awareness of autism and the flexibility of the diagnostic tools used, we've recently been diagnosing people with autism who previously would have received other diagnoses or gone unidentified," Willingham writes.

Autism rates might actually go down after the release of DSM-V (scheduled for May 2013); the proposed revisions will reduce four current categories to one—autism spectrum disorder, or ASD. [see here.]

You can read the rest of the article at [Discover]